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United States Patent |
5,083,373
|
Hamburgen
|
January 28, 1992
|
Method for providing a thermal transfer device for the removal of heat
from packaged elements
Abstract
In order to provide thermal coupling of a package, particularly a package
containing electronic components, and a heat sink, a thermal transfer
assembly includes a first assembly having a group of generally parallel
cooling fins coupled to the package. Coupled to the heat sink, such as
cooling plate, is a second assembly also including a plurality of
generally parallel cooling fins. The second set of cooling fins is
positioned on the heat sink so that when the heat sink is in a
predetermined position with respect to the package, the cooling fins
overlap. The overlapping cooling fins permit efficient transfer of heat
thus permitting heat generated in the package to be conveyed to the heat
sink. The overlapping fins also permit convenient disassembly and
reassembly for test and maintenance procedures. Techniques for fabrication
of the thermal transfer assembly are described along with procedures for
improving the operation of the heat transfer assembly. Parameters
optimizing the performance of thermal transfer assembly are discussed. The
individual components of the thermal transfer unit can be used separately
as heat exchange units.
Inventors:
|
Hamburgen; William R. (2098 Cedar Ave., Menlo Park, CA 94025)
|
Appl. No.:
|
704898 |
Filed:
|
May 21, 1991 |
Current U.S. Class: |
29/890.03; 29/445; 29/462; 29/469; 29/829; 257/714; 257/722; 257/E23.09; 257/E23.094 |
Intern'l Class: |
F28F 013/14 |
Field of Search: |
29/829,890.03,445,462,464,469
361/386-389
174/163
228/183,212
165/185,80.3,80.4
437/902
357/81
|
References Cited
U.S. Patent Documents
2371847 | Mar., 1945 | Saunders et al. | 228/212.
|
4092697 | May., 1978 | Spaight | 357/81.
|
4226281 | Oct., 1980 | Chu | 165/80.
|
4235283 | Nov., 1980 | Gupta | 165/80.
|
4381032 | Apr., 1983 | Cutchaw | 165/80.
|
4498530 | Feb., 1985 | Lipschutz | 165/185.
|
4649990 | Mar., 1987 | Kurihara et al. | 357/81.
|
Foreign Patent Documents |
0048992 | Apr., 1982 | EP | 29/829.
|
Primary Examiner: Cuda; Irene
Attorney, Agent or Firm: Holloway; William W.
Parent Case Text
This is a continuation of Ser. No. 629,086 filed on Dec. 17, 1990,
abandoned, which is a continuation of Ser. No. 254,867 filed on Oct. 5,
1988, abandoned, which is a continuation of copending application Ser.
No. 145,641 filed on Jan. 12, 1988, now U.S. Pat. No. 4,800,956 which was
a continuation of copending application Ser. No. 856,294 filed on Apr. 25,
1986, now abandoned.
Claims
What is claimed is:
1. The process for fabricating a thermal transfer device comprising the
steps of:
positioning a strip of a spacer material between each member of a first set
of parallel thermally conducting unassembled cooling fins and an adjacent
member of a second set of parallel thermally conducting unassembled
cooling fins interleaved with said first member;
connecting said first set of cooling fins to a first thermally conducting
base member to form a first thermal transfer unit;
connecting said second set of thermally conducting cooling fins to a second
thermally conducting base member to form a second thermal transfer unit;
and
removing said spacer material, wherein said first and said second set of
cooling fins are interleaved in an operative thermal transfer
configuration.
2. The process for fabricating a thermal transfer device of claim 1 further
comprising the steps of coupling said first thermal transfer unit to a
heat source and coupling said second thermal transfer unit to a heat sink.
3. The process for fabricating a thermal transfer device of claim 2 further
comprising the steps of:
coupling said heat sink to a first structure;
coupling said heat source to a second structure; and
coupling said first and said second structure wherein said first and said
second sets of fins can be engaged into and disengaged from said
protective configuration.
4. The process for fabricating a thermal transfer device of claim 1 further
comprising the steps of:
positioning spacer material between each member of a third set of parallel
thermally conducting unassembled cooling fins and an adjacent member of a
fourth set of parallel thermally conducting unassembled cooling fins
interleaved with said third set;
connecting said third set of cooling fins to said second thermally
conducting base member to form an intermediate thermal transfer unit; and
connecting said fourth set of thermally conducting cooling fins to a third
thermally conducting base member to form a second thermal transfer unit,
wherein said third and said fourth set of cooling fins are interleaved in
said operative thermal transfer configuration.
5. A method for providing a thermal transfer device
having a first thermal transfer unit, and
a second thermal transfer unit, said method comprising the steps of:
positioning a strip of a spacer material between each member of a first set
of parallel thermally conducting unassembled cooling fins and an adjacent
member of a second set of parallel thermally conducting unassembled
cooling fins interleaved with said first member;
bonding said first set of cooling fins to a first thermally conducting base
member to form said first thermal transfer unit;
bonding said second set of thermally conducting cooling fins to a second
thermally conducting base member to form said second thermal transfer
unit; and
removing said spacer material, wherein said first and said second set of
cooling fins are interleaved in an operative thermal transfer
configuration.
6. The method of claim 5 further comprising the step of fabricating said
fins and selected said spacer material according to the relationship
L.sup.2 =S*B*K.sub.P /K.sub.G
where L is a length of an overlap between said fins in said operative
configuration, S is the thickness of said spacer material, B is a
thickness of said fins, K.sub.P is a thermal conductivity of said fins and
K.sub.G is a thermal conductivity of material between said fins in said
operative configuration.
7. A method for providing a thermal transfer device
having a first thermal transfer unit, and
a second thermal transfer unit, said method of comprising the steps of:
positioning a strip of spacer material between each member of a first set
of parallel thermally conducting unassembled cooling fins and an adjacent
member of a second set of parallel thermally conducting unassembled
cooling fins interleaved with said first member;
connecting said first set of cooling fins to a first thermally conducting
base member to form said first thermal transfer unit;
connecting said second set of thermally conducting cooling fins to a second
thermally conducting base member to form said second thermal transfer
unit;
removing said spacer material, wherein said first and said second set of
cooling fins are interleaved in an operative thermal transfer
configuration;
coupling said second thermal transfer unit to a heat sink;
coupling said heat source to a second structure; and
coupling said first and said second structure wherein said first and said
second sets of fins can be engaged into and disengaged from said operative
configuration.
8. The method of claim 7 further comprising the step of:
compensating for thermal expansion of said first structure by orienting
said first set of fins generally parallel to a selected point on said
structure.
9. A method of fabricating a thermal transfer device said method of
comprising the steps of:
positioning a strip of spacer material between each member of a first set
of parallel thermally conducting unassembled cooling fins and an adjacent
member of a second set of parallel thermally conducting unassembled
cooling fins interleaved with said first member;
connecting said first set of cooling fins to a first thermally conducting
base member to form said first thermal transfer unit;
connecting said second set of thermally conducting cooling fins to a second
thermally conducting base member to form a second thermal transfer unit;
and
removing said spacer material, wherein said first and said second set of
cooling fins are interleaved in an operative thermal transfer
configuration
positioning spacer material between each member of a third set of parallel
thermally conducting unassembled cooling fins and an adjacent member of a
fourth set of parallel thermally conducting unassembled cooling fins
interleaved with said third set;
connecting said third set of cooling fins to said second thermally
conducting base member to form an intermediate thermal transfer unit; and
connecting said fourth set of thermally conducting cooling fins to a third
thermally conducting base member to form a second thermal transfer unit,
wherein said third and said fourth set of cooling fins are interleaved in
said operative thermal transfer configuration.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the cooling of components and, more
particularly, to the cooling of the electronic packages in the operating
configurations.
2. Description of the Related Art
As the density of semiconductor gates or elements associated with each
electronic package has increased, the solution of the problem of removal
of the heat, generated within the package has become increasingly
difficult. The movement of gas directly over the packages has proven
inadequate to maintain the packages within acceptable temperature ranges
as the density of elements in the package has increased. To improve the
efficiency of the heat removal, a cooling plate or other heat sink can be
placed in contact with the package. When a plurality of components must be
cooled, as can, for example, occur for the circuit boards of a data
processing system, the use of a cooling plate frequently causes excessive
stress on the packages when an attempt is made to insure that all
components are in good thermal contact with the cooling plate. When
physical contact between the component to be cooled and the cooling plate
cannot be assured, then a gas with thermal properties superior to air can
be used by placing the component and the cooling plate in an enclosed
container. The cooling gas within the container, however, can become
contaminated and the superior thermal properties compromised. The problem
of providing good thermal contact between the plate and the package is
further complicated by the need to access the electronic packages for
testing or for maintenance.
Referring now to FIG. 1a, FIG. 1b and FIG. 1c, three techniques for
providing removal of heat from component packages 15, according to the
related art is shown. The component package is typically coupled to a
circuit board 10, i.e. by solder bumps. The apparatus in each case
provides for the transfer of heat from the package to the cooling plate 11
via an intermediate element. The cooling plate can have additional cooling
apparatus associated therewith such as apparatus for permitting a cooling
liquid to flow through channels in the cooling plate. In FIG. 1aa
spring-loaded piston 12 (with spring 18) is forced into contact with the
package 15. The heat must be transferred first from the package 15 to
piston 12 and then from piston 12 to the cooling plate 11. In the
implementation of this apparatus, a He gas atmosphere is used to improve
the thermal contact between the piston 12 and the package 15 and the
piston 12 and the plate 11. Similarly, in FIG. 1b, a screw-clamped piston
13 is coupled to the cooling plate 11. In this arrangement, the screw must
be adjusted during the manufacture of the component. A thermal transfer
material 14 is placed between piston 13 and package 15. It will be clear
that the configurations of FIGS. 1a and 1b can cause unacceptable stress
to be applied to the chip.
In FIG. 1c, a spreading element 17 is coupled to the package 15 by solder
material 16. The heat is transferred from the chip 15 through the solder
material 16 to the spreading element 17. From the spreading element 17,
the heat is transferred to the cooling plate 11. To obtain a low thermal
resistance, a gas (H.sub.2) is needed to improve the thermal coupling
between spreader 17 and cooling plate 11. In addition, the apparatus of
FIG. 1c and the apparatus of FIG. 1b do not permit the convenient
disassembly and reassembly, there being no convenient method to determine
when a good thermal contact is established.
Each of these heat transfer devices described above requires a substance to
improve the thermal coupling. The presence of these substances complicates
the manufacture and repair of the packages and related circuits.
Referring next to FIG. 2, an apparatus for providing thermal coupling
between a cooling plate 11 and a package 15 is shown. The thermal coupling
apparatus includes a holder 21 for engaging a plurality of T-shaped
elements 25. The holder 21 engages a spring element 26. The spring element
26 engages a structure 11a of the cooling plate. The spring element forces
the T-shaped elements against the package 15. The T-shaped structures are
positioned to interleave with structures 11b of the cooling plate. A major
limitation of this apparatus is the effectiveness of the thermal contact
between the T-shaped elements 25 and the package 15. In addition, this
configuration suffers from a lack of flexibility in that the structures
11a and the structures 11b must be fabricated in the cooling plate 11 when
the position of the chip has been defined.
A need has therefore been felt for apparatus and method for providing for
the removal of heat from a semiconductor element that provides a good
thermal coupling and can be conveniently disassembled and reassembled.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved apparatus
and method for cooling of electronic packages.
It is another object of the present invention to provide apparatus and
method for cooling an array of electronic packages.
It is a still further object of the present invention to provide apparatus
and method for cooling electronic packages whereby the cooling mechanism
can be easily removed from and recoupled to the electronic package.
It is yet another object of the present invention to provide apparatus and
method for thermally coupling a cooling plate and a package that does not
require the use of additional materials to improve the thermal transfer.
It is yet a further object of the present invention to provide a method for
fabrication of a heat exchange elements, elements that can be used for
thermal coupling to the ambient environment.
The aforementioned and other objects are accomplished, according to the
present invention, by thermal coupling a first plurality of plates or
thermal transfer fins, the plates being fabricated from a material having
good thermal conductivity, to a package requiring cooling. The plates of
the first plurality of plates are generally positioned to be parallel to
the remaining plates. A second plurality of plates or thermal transfer
fins is coupled to a heat sink such as a cooling plate. The second
plurality of plates is also fabricated from a material having good thermal
conductivity and also has a plurality of generally parallel plates. The
heat sink can be positioned relative to the electronic package so that the
first plurality of plates is interleaved with the second plurality of
plates. The extensive overlapping areas of the two sets of plates results
in an efficient exchange of heat. Thus the heat can be conveyed from the
electronic package through the first and second plurality of plates to the
heat sink. The interwoven plates can be easily separated and reengaged
providing for convenient testing and maintenance. An intermediate element
can be placed between the sets of plates to permit flexibility in the
positioning and orientation of the sets of plates. A method of fabrication
of the thermal transfer fins can be used to provide a thermal exchange
element.
These and other features of the present invention will be understood upon
reading of the following description along with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1a, FIG. 1b and FIG 1c, illustrate related techniques for thermal
coupling of a cooling plate and an electronic package.
FIG. 2 shows a cross-sectional view of an apparatus providing thermal
coupling between a cooling plate and an electronic package according to
the related art.
FIG. 3 is a cross-sectional view of the thermal transfer assembly for
providing cooling of a package according to the present invention.
FIG. 4 is a perspective view of the thermal transfer assembly indicating
various parameters used in analyzing the performance.
FIG. 5 is a perspective view of the cooling apparatus of the present
invention illustrating the use of a coupling element for providing
flexibility in the orientation and position on the cooling apparatus of
the present invention.
FIG. 6 is a cross-sectional view of the thermal transfer assembly
illustrating the fabrication technique.
FIG. 7 is a top view of a board having a plurality of thermal transfer
units coupled thereto illustrating how a difference in thermal expansion
between the board and the cooling plates can be accommodated.
FIG. 8 illustrates a technique for facilitating the coupling of the upper
and lower portions of the thermal transfer assembly.
FIG. 9a and 9b are front and side views respectively of thermal transfer
fins shaped to facilitate the coupling of the two portions of the thermal
transfer assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
1. Detailed Description of the Figures
FIG. 1a, FIG. 1b, FIG. 1c and FIG. 2 have been described with reference to
the related art.
Referring next to FIG. 3, the configuration of the present invention is
illustrated. The cooling plate 11 and a package 15 have a thermal transfer
assembly 30 coupled there between. The thermal transfer assembly 30
includes a first or upper thermal transfer portion 31 and a second or
lower thermal transfer portion 32. The first and second thermal transfer
portions, 31 and 32, include a base element, 311 and 321 respectively and
a plurality of planar members or thermal transfer fins, 312 and 322
respectively. The first thermal transfer portion 31 is coupled to the
cooling plate 11 and disposed, when the thermal transfer fins are in the
operational position, opposite the semiconductor package 15 requiring
cooling. Coupled to the semiconductor package 15 is the thermal transfer
portion 32. The thermal transfer fins 312 and the thermal transfer fins
322 are interleaved when the cooling plate is in the operational position.
The operational position is determined by positioning apparatus. In FIG.
3, two types of positioning apparatus are shown. Element 37 illustrates
the use of a hinge mechanism to control the relative positions of the
upper and lower portions of each heat assembly apparatus. The hinge
mechanism forces the circuit board 10 and the cooling plate 11 to be
rotated in and out of the interleaved position. This arrangement operates
most effectively when the elements of the transfer assemblies are
perpendicular to the axis of the hinge. Referring next to elements 38 and
39 of FIG. 3, the circuit board and the cooling plate can have a relative
position determined by two or more guides 38. These guides can be used to
move the thermal transfer fins into the operational position without
causing damage to the cooling assembly.
Referring to FIG. 4, a cooling assembly is shown along with designated
dimension identifiers. For ease of discussion, certain simplifying
approximations are made. For example, the length and width of the thermal
transfer assembly 30 are assumed to be equal and are designated by D.
Similarly, the thickness of the individual thermal transfer fins 312 and
322 of the upper assembly 31 and the lower assembly 32, respectively, are
assumed to be equal and are designated by B. The upper and lower sets of
thermal transfer fins are assumed to be fabricated of the same material,
symmetrically disposed with respect to each other and separated by a gap
designated by S. The sets of thermal transfer fins 312 and 322 overlap
each other by an amount designated by L. The heat transfer between the end
of the cooling fins and the base of the opposite assembly is assumed in
this analysis to be unimportant. A quantitative discussion of the heat
exchanges between the upper and lower assemblies can be understood,
assuming a linear temperature profile along each of the heat transfer
fins, as follows. The number of plates of the cooling assembly is given by
Number of Plates=N.sub.P =D/(S+B) (1)
Similarly, the number of gaps is given by
Number of Gaps=NG=D/(S+B) (2)
If the thermal conductivity of the plate material is determined to be
K.sub.P, then the thermal resistance r.sub.P of each plate is given by
r.sub.P =L/KP*B*D (3)
If the thermal conductivity of the gap material is determined to be
K.sub.G, then the thermal resistance r.sub.G across each gap is given by
r.sub.G =S/KG*L*D (4)
The total thermal resistance can be approximated by
R=R.sub.P +R.sub.G =r.sub.P /N.sub.P +r.sub.G /N.sub.G (5)
Combining equations (1), (2), (3), (4) and (5), then
R={(S+B)/D.sup.2 }*{L/K.sub.P *B+S/K.sub.G *L} (6)
For a given gap S, the minimum value of R is obtained when
L/K.sub.P *B*D=S/K.sub.G *D*L (7)
L.sup.2 =S*B*K.sub.P /K.sub.G (8)
Therefore, using the approximations and assumptions described above, the
maximum heat transfer, i.e. the least thermal resistance will occur when
the length squared is equal to the width of the thermal transfer fins
times the width of the gap times the ratio of the thermal conductivity of
the thermal transfer fin and the thermal conductivity of the gap material.
Further analysis demonstrates that, for a given value of gap spacing S,
the minimum thermal resistance will occur when S=B.
Referring next to FIG. 5, a further advantage of the use of the thermal
transfer fins attached to the electronic package and to the cooling plate
is seen. In the case that the thermal transfer fins (or parallel plates)
do not have the proper orientation for interleaving, an intermediate
coupling member 51 can be used to provide a thermal path. The coupling
member 51 includes a base 511 with two sets of thermal transfer fins
attached thereto. One set of thermal fins 512 is positioned to be
interleaved with the thermal transfer fins 322 coupled to the cooling
package, while the second set of thermal transfer fins 513 is adapted to
be interleaved with the thermal transfer plates 312 coupled to the cooling
plate. It will be clear that the coupling device can compensate for
improper orientation, improper lateral positioning, and for extended
separation between the electronic component and the cooling plate. In FIG.
5, the two groups of parallel plates are oriented at right angles to each
other. It will be clear that any arbitrary angle is possible between these
groups of plates. Viewed in another manner, without the intermediate
coupling member 51, the interleaved groups of parallel plates permit two
translational degrees of freedom, separation and motion parallel to the
plates, and one rotational degree of freedom about an axis perpendicular
to the interwoven plates. The intermediate coupling member permits an
additional rotational degree of freedom and an additional translational
degree of freedom between the groups of plates associated with the cooling
package and the plates associated with the cooling plate.
Referring next to FIG. 6, a convenient technique for the fabrication of the
thermal transfer unit is illustrated. A tape material 63 having the
thickness of the desired gap S between cooling fins is intertwined between
the thermal transfer fins 312 and 322 of the upper and lower assemblies,
respectively. The thermal transfer fins are forced against two base plates
311 and 321, held in position by a jig illustrated by elements 67a and
67b, and soldered to the base plates at solder joints 69. The base plates
can be coupled to a package and to the cooling plate when the package and
the cooling plate are in the operational position. The two assemblies can
then be separated, the tape removed and the thermal transfer unit
reassembled without the tape. Each assembly of the thermal exchange unit
also can be used as a heat exchange (i.e. with the environment) unit.
Because the heat exchange unit does not require the interwoven plates, the
exchange units can be assembled using only the tape and not the second set
of plates. In this assembly technique, the tape can extend beyond the
sides of the plates, thereby permitting all of the plates to be coupled to
the base element.
Referring to FIG. 7, a procedure for accommodating a difference in thermal
expansion between the cooling plate and the material, such as a wiring
board, to which the packages to be cooled are coupled is illustrated. In
this procedure, a point 70 on the wiring board and a similarly positioned
point on the cooling plate are selected as a reference axis and the
relative position of these two points is held fixed. The thermal transfer
assemblies 71 are then coupled so that the cooling fins are generally
parallel to the radius from the axis defined by the two points. Similarly,
the guide pins 74, coupled to a board or plate with one set of the thermal
transfer components, are inserted in guide slots 73 that are also parallel
to the radius from reference axis 70. Thus, the relative expansion or
contraction of the cooling plate and the wiring board will result in the
relative motion of the upper and lower assemblies in such a manner that
the cooling fins associated with each assembly will move along one of the
translational degrees of freedom of the thermal transfer assembly.
Referring next to FIG. 8, a technique for improving the engagement of the
two portions of the thermal transfer assembly is shown. When the thermal
transfer fins are moved from a separated position to an interleaved
position, any perturbations in the position of the thermal transfer fins
may result in the contact of one or more of the thermal transfer fins with
at least one thermal transfer fin of the opposite portion of the thermal
transfer assembly. The width of the thermal transfer fins can result in a
binding action between thermal transfer fins of each assembly. The binding
action can result in the destruction of the bound cooling fins and through
a domino action, result in the destruction of the thermal transfer
assembly. To reduce the possibility of binding between thermal transfer
fins on the separate assemblies, the ends of the thermal transfer fins are
fabricated with a wedge shape. The wedge shape permits the thermal
transfer fins to overlap with a minimum risk of binding.
Referring next to FIG. 9a and 9b, a further improvement in the structure of
the thermal fins is illustrated that facilitates the movement of the two
portions of the thermal transfer assembly into the interleaved position.
The shape of the thermal transfer fins are fabricated so that a reduced
portion of the fins come into the vicinity of cooling fins of the opposite
assembly portion during initial engagement. In the event of contact
between opposite assembly portion thermal transfer fins, the shape of the
thermal transfer fins can cause the contacting portions of the thermal
transfer fins to slide past each other, thereby reducing the chances for
destructive binding of the thermal transfer fins. Although the narrow
region shown as 81 in FIG. 9b has a finite length, it will be clear that
the thermal transfer fin can be pointed. It will also be clear that the
shape illustrated in FIG. 9a and 9b can be combined with the wedge-shaped
end shown in FIG. 8 for the thermal transfer fins.
FIG. 9b also indicates a further improvement of the present invention
important for certain applications. In this improvement, the cooling fins
have portions 91 (indicated by dotted lines) removed from the bottom of
the cooling fins. These removed portions may be utilized when the base
element and the cooling fins are fabricated from different materials and
have thermal expansion coefficients sufficiently different to compromise
the coupling between cooling fins and the base element. The removed
portions 91 provide for the integrity of the coupling despite the
differing thermal expansion coefficients. (The base element material may
be chosen to be consistent with the thermal expansion coefficient of the
package material or whatever material to which the base element is
coupled.)
2. Operation of the Preferred Embodiment
With respect to the analysis given for FIG. 4, a more complete analysis,
which confirms the original calculation upon which the invention was
developed, results in
R.sub.EXACT =L*(S+B)*O/K.sub.P *B*D.sup.2 (9)
where
O=[1+2*(1+cos hw)/w sin hw] (10)
and
w.sup.2 =4*L.sup.2 *K.sub.G /K.sub.P *S*B (11)
Equation (6) and equation (9) yield thermal resistances that are within 20%
of each other for any value of the parameters. As an example of typical
values, when S=69 um, B=69 um, D=14.14 mm, L=7.38 mm and the thermal
conductivities for copper and air are used, then R=0.439.degree. C./W,
while R.sub.EXACT =0.500.degree. C./W.
Other features of the heat transfer assembly can be understood by
substituting typical values in the foregoing equations. For example,
relatively small departures from the optimum length of the thermal
transfer fins result in small changes from the optimum value of R, i.e.
the thermal resistivity. Therefore, extreme accuracy in the implementation
of the length of the thermal transfer fins is not required. However, the
tapering configuration shown in FIG. 9b can affect the value of the
thermal resistivity of the thermal transfer assembly. The foregoing
analysis has been based on the assumption that the thermal transfer fins
for each assembly are symmetrically positioned with respect to the thermal
transfer fins of the other assembly, i.e. the gap S is equal for the whole
assembly. Analysis shows that any departures from the symmetrical gap S
results in decreased thermal resistivity. In the limiting case where S=0,
i.e. the thermal transfer fins are touching, the lowest resistivity can be
achieved.
Although the foregoing description has been given in terms of the cooling
of electronic components, it will be clear that the present invention can
be used advantageously to maintain any type of component within a
predetermined temperature range either by heating or by cooling the
component. In addition, because the individual components of the thermal
transfer units can be used as heat exchange elements for transfer for
coupling to the environment, the process for manufacturing the thermal
transfer units can be used to manufacture the individual heat exchange
units. This manufacturing process can produce heat exchange units of
dimensions that would be difficult to fabricate by ordinary machining or
casting techniques. In addition, the cooling fins can be mounted directly
on the component or package to be cooled, the component or package then
acting as the base element for the cooling fins.
It will also be clear that the foregoing discussion will also be valid for
cooling structures implemented by interleaved pins or brushes. These pins
or brushes can be implemented to approximate the planar structure of the
cooling fins described above or can be implemented to have a different
structural organization.
The foregoing description is included to illustrate the operation of the
preferred embodiment and is not meant to limit the scope of the invention.
The scope of the invention is to be limited only by the following claims.
From the foregoing description, many variations will be apparent to those
skilled in the art that would yet be encompassed by the spirit and scope
of the invention.
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